Field of the Invention
The invention relates to a linear actuator, and more particularly to a linear actuator improving the offset in a linear movement.
Description of Related Art
With respect to the ACME screw and ball screw transmission, the rotary motion is conversed into linear motion by rotating the nut disposed on the screw. However, the inaccuracy during the conversion may occur due to the process capability, and the tolerances of geometry, size and linearity.
In order to enhance the accuracy, the WO2014092255 patent disclosed a tube holds a positioned linear bearing to support the inner tube and guide the linear motion thereof. In addition, it also disclosed a non-circular restricting unit disposed on the inner tube and reciprocating along the inner tube thereby restricting the rotation between the inner tube and the outer tube.
Although the above conventional technology can provide the support and guide during the linear motion to prevent from unnecessary rotation, the offset compensated by the gap between ball and the ball retainer of the linear bearing is too limited to improve the accuracy during the linear motion.